The present invention pertains to a ballnose cutting tool, as well as the ballnose cutting insert used therewith. While the ballnose cutting tool has other applications, one useful application is to use the ballnose cutting tool for milling operations in metal machining. The ballnose cutting tool comprises a plurality of identical ballnose cutting inserts wherein each ballnose cutting insert is retained in an insert-receiving pocket contained in a ballnose tool holder. More specifically, the present invention pertains to a ballnose cutting tool that comprises a ballnose tool holder containing a plurality of insert-receiving pockets and a plurality of ballnose cutting inserts. Each ballnose cutting insert and its corresponding insert-receiving pocket exhibits a structure that provides for the secure retention of the ballnose cutting insert to the ballnose tool holder. Further, the present invention pertains to a ballnose cutting tool wherein the ballnose cutting insert exhibits a geometry so as to not contact the machined surface of a workpiece upon deflection of the ballnose cutting tool.
Some ballnose cutting tools comprise two identical ballnose cutting inserts wherein each ballnose cutting insert is retained in its respective insert-receiving pocket contained in the ballnose tool holder for applications such as, for example, milling operations in metal machining. The ballnose cutting inserts disclosed herein are particularly useful in die and mold profile milling applications and profile milling high temperature alloy components. There is a common concern when using ballnose cutting tools under severe cutting conditions because the ball shape cutting insert is likely to rotate in the insert-receiving pocket on the ballnose tool holder. A typical ballnose cutting insert that has elongate cutting edge provides two elongate cutting edges. Each elongate cutting edge comprises a curved cutting edge portion with circular diameter to the ballnose cutting diameter and a straight cutting edge portion. Due to the relatively larger radius and longer curved arc of the curved cutting edge portion plus the heavy cutting conditions, it is difficult to reliably and precisely secure the ballnose cutting insert in an insert-receiving pocket in the ballnose tool holder. In some other cases, in order to achieve a secure and precise position, the ballnose cutting insert and the corresponding pocket on a tool holder become complex in geometry and difficult to manufacture. It would therefore be highly desirable to provide an improved ballnose cutting tool, as well as an improved ballnose cutting insert, wherein there is provided a reliable axial support for the ballnose cutting insert to prevent the ballnose cutting insert from rotating in the pocket of a ballnose tool holder during the heavy machining processes
Further, a typical ballnose cutting tool can experience deflection during the machining process, especially during a heavy machining process. Heretofore, such deflection has caused a portion of the cutting edge to contact the machined surface of the workpiece thereby damaging the surface of the workpiece. Such damage can render the workpiece unsuitable. Therefore, it would be highly desirable to provide an improved ballnose cutting tool, as well as an improved ballnose cutting insert, wherein the cutting edge of the ballnose cutting insert would not contact the machined surface of the workpiece upon deflection of the ballnose cutting tool.